A glucose tolerance test is a medical procedure in which glucose is administered to a subject, e.g., an animal, to determine how quickly the glucose is cleared from the blood of the subject. The glucose is typically given orally so that the common test is typically called an oral glucose tolerance test (OGTT). This test is frequently used to evaluate the status of metabolic pathways in a human or animal body. From the results of the test, metabolic disorders can be diagnosed or the impact of drugs on physiology can be determined.
To evaluate the effects of drugs on metabolism or their impact on metabolic diseases such as diabetes mellitus, the standard approach is to use mice or rats for the necessary in vivo experiments. However, the metabolism of mice and rats does not reflect all aspects of the human metabolic system. A drug that is very effective in mice and rats might not have any impact on humans. Conversely, a drug that is ineffective in mice and rats might be very effective on humans. Therefore, factors that may influence metabolism and lead to erroneous experimental results must be controlled or mitigated. Moreover, although the standard approach is to use mice and rats, anthropoid apes such as Cynomolgus monkeys are generally considered to be among the animals that best reflect the human metabolic system due to their gene homology to humans exceeding 95%.
Animals including mice, rats and monkeys are very sensitive to artificial stimulations and environmental influences. As a consequence, it is often difficult to obtain stable and reproducible data from an animal experiment if the experiment is conducted with irritated or even frightened animals. This is true for an oral glucose tolerance test. For example, blood glucose levels of mice, rats and monkeys rise immediately if they are merely touched by a human. If these animals feel real pain, for instance in the course of blood sampling, results show an even more dramatic increase in blood glucose levels.
Thus, it is laborious and complicated to achieve results which are reliable, reproducible and significant when conducting an animal experiment, particularly an OGTT, with animals such as mice, rats and monkeys.
Therefore, it is the object of the present invention to provide a method for improving the accuracy of the results obtained from an animal experiment.